The gains -- after the close of regular trading -- have brought
Shake Shack's market capitalization to about $2.8 billion,
compared with the $2.85 billion of Wendy's or $2.81 billion for
Papa John's.

But Wendy's has 95 times as many stores, and 12 times
Shake Shack's annual sales, according to Nation's Restaurant
News.

A single Shake Shack
location is worth nearly $40 million. That compares with
about $10 million for a Chipotle location and $3 million for a
McDonald's restaurant.

So why is Shake Shack's valuation so high? Because investors
believe it has huge growth potential - even if the company
itself says it isn't trying to become a massive
chain. Executives say there are plans to open "at least 12
restaurants per year." That rate of growth puts the company far
behind competitors with thousands of locations.

"To be sure, investors are betting that Shake Shack will grow to
become the size of a big chain someday — though the company
itself says it plans to grow only to about 450 locations in the
US, which will make it something of a destination fast-casual
concept, rather than an everyday lunch place," Jonathan
Maze writes in Nation's Restaurant News.

Still, Shake Shack's high-quality, ethically sourced food and
excellent customer service have drawn many comparisons between it
and Chipotle, which has seen business explode in recent
years. While McDonald's and Wendy's are trying to emulate
Shake Shack's strategy, they are a long way from being able to
offer a similar experience.